1 Error + need an advice from you guys

[Project try]

Hey guys , Sorry for asking a lot :D

basically I'm reading this book called c++ gui programming with qt 4 " I'm using qt 5 " and he uses lots of examples to teach, should I write the example that is in the book and compile it myself and then study it line by line and then rewrite it again to remember what these functions / classes are for ?

--

the error is basically this :

bq. error: C2664: 'QBoxLayout::addWidget' : cannot convert parameter 1 from 'QHBoxLayout *' to 'QWidget *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

--

and these lines are the problem:

@QHBoxLayout *topLeftLayout=new QHBoxLayout; // declared this

QVBoxLayout *LeftLayout=new QVBoxLayout;
LeftLayout->addWidget(topLeftLayout); // here is the problem

@

also if I may ask what's the difference between autodefault and set default ? and why is set default has no parameters in the definition ?

also , does the compiler sets everything for you , for example when I create a layout with some things , also create a layout with same or other things in the same dialog or window , how does the program sets them so they won't screw up each other " example: two push buttons are in the same place "

thanks a lot guys ^^

[ChrisW67]

The call should be to addLayout() not addWidget().

[SGaist]

Hi,

You are trying to add a layout which is not a QWidget.

What you must use is addLayout.

The compiler is innocent, it only compiles code. The widget "layouting" is done by the layout manager (e.g. QVBoxLayout) at run time when the widgets are created, added to it and shown.

[Project try]

Thanks guys ,

[Project try]

Hey guys , sorry about asking again , when I compile now I get 4 errors which is about linking , when I delete Q_OBJECT from the header of my class the problem goes away , but in the book it says when you use slots and signals you should include it , what do you guys think ?

Errors:

bq. finddialong.obj:-1: error: LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl Finddialong::metaObject(void)const " (?metaObject@Finddialong@@UEBAPEBUQMetaObject@@XZ)

finddialong.obj:-1: error: LNK2001: unresolved external symbol "public: virtual void * __cdecl Finddialong::qt_metacast(char const *)" (?qt_metacast@Finddialong@@UEAAPEAXPEBD@Z)

finddialong.obj:-1: error: LNK2001: unresolved external symbol "public: virtual int __cdecl Finddialong::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Finddialong@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)

finddialong.obj:-1: error: LNK2001: unresolved external symbol "public: static struct QMetaObject const Finddialong::staticMetaObject" (?staticMetaObject@Finddialong@@2UQMetaObject@@B)

debug\untitled10.exe:-1: error: LNK1120: 4 unresolved externals

[JKSH]

Hi,

[quote]in the book it says when you use slots and signals you should include it[/quote]Yes, the book is correct.

[quote]finddialong.obj:-1: error: LNK2001: unresolved external symbol “public: virtual struct QMetaObject const * __cdecl Finddialong::metaObject(void)const “ (?metaObject@Finddialong@@UEBAPEBUQMetaObject@@XZ)[/quote]To avoid this error, run qmake after you add "Q_OBJECT" to the header.

[qxoz]

@Project try, take a look to "qt5-book-code":https://github.com/mutse/qt5-book-code it could be useful for continue learning

[Project try]

@qxoz thanks , I'll check them out.

I'm sorry for posting late guys , I had to sleep + go to college :(

anyways when I installed qt it came with it a command prompt , when I opened it and wrote qmake it says you can place any variable assigement in option will be parsed and there's some option like -o file

i don't know what to do , I'm new to this , usually I just run the compiler and it just works.

[Project try]

Hey guys , I've gone to folder that the project is in " from command line that came with qt " and used qmake but it justs doesn't show anything , when I tried to compile it from qt creator it gives me the same error ?

maybe because I used qmake in the project ? theree's two folders when I create a new project , one is for the project files and the other is called build ....

[Project try]

I guess nothing worked :(

1- tried using qmake in the command line , didn't work
2- cleaned the project then ran qmake and build it and it did not work
3- used a new project and it did not work

it just gives the same error and it says nameoffile.obj not found " the same error "

[SGaist]

Windows is not especially user/developer friendly on the command line.

Where did you call qmake ? Did you call nmake afterwards ?

[Project try]

I called qmake in the command line , also in the project " when you right click " you'll find an option called " qmake " , what is nmake ? becaus when I tried it in the command line it says there's no such thing.

[SGaist]

nmake is the command that will read the Makefiles generated by qmake and call the compiler/linker etc…

But I am just realizing… What version of Qt is installed ? VSXXXX or MinGW ? If the later, you need to call mingw32-make after qmake

[Project try]

Sorry for posting late , I have the qt 5.2.1 ( msvc 2010 , 32bit) if this is what you're looking for .. the creator is 3.0.1

[SGaist]

Are you sure you are using the correct command line ?

Before taking too much time with it, does Qt Creator work correctly when building a default created application ? (using file -> new project -> use all defaults -> build )

[Project try]

Yes it works fine with the default building , it shows the main window just fine , as I said when I remove q_object the problem goes away , not sure why.

sorry for wasting your time with me :(

[Project try]

Let me just post the code here so you can check ^^

the interface for the class:

@#ifndef FINDDIALONG_H
#define FINDDIALONG_H
#include<QDialog>

class QCheckBox;
class QLabel;
class QLineEdit;
class QPushButton;

class Finddialong : public QDialog
{
Q_OBJECT
public:
Finddialong(QWidget *parent=0);
signals:
void findNext(const QString &str,Qt::CaseSensitivity cs);
void findPrevious(const QString &str,Qt::CaseSensitivity cs);
private slots:
void findClicked();
void enablefindButton(const QString &text);
private:
QLabel *label;
QLineEdit *lineEdit;
QCheckBox *backwardCheckBox;
QCheckBox *caseCheckBox;
QPushButton *findButton;
QPushButton *closeButton;
};

#endif // FINDDIALONG_H
@

the implement for the class:

@#include<QtGui>
#include "finddialong.h"
#include<QHBoxLayout>
#include<QVBoxLayout>
#include<QPushButton>
#include<QLabel>
#include<QLineEdit>
#include<QCheckBox>

Finddialong::Finddialong(QWidget *parent) : QDialog(parent)
{
label=new QLabel(tr("Find &what:"));
lineEdit = new QLineEdit;
label->setBuddy(lineEdit);
caseCheckBox=new QCheckBox(tr("Match &case"));
backwardCheckBox=new QCheckBox(tr("Search &backward"));
findButton=new QPushButton(tr("&Find"));
findButton->autoDefault();
findButton->setEnabled(false);
closeButton = new QPushButton(tr("close"));
connect(lineEdit,SIGNAL(textChanged(const QString &)),this,SLOT(enableFindButton(const QString &)));
connect(findButton,SIGNAL(clicked()),this,SLOT(findClicked()));
connect(closeButton,SIGNAL(clicked()),this,SLOT(close()));
QHBoxLayout *topLeftLayout=new QHBoxLayout;
topLeftLayout->addWidget(label);
topLeftLayout->addWidget(lineEdit);
QVBoxLayout *LeftLayout=new QVBoxLayout;
LeftLayout->addLayout(topLeftLayout);
LeftLayout->addWidget(backwardCheckBox);
LeftLayout->addWidget(caseCheckBox);
QVBoxLayout *rightLayout=new QVBoxLayout;
rightLayout->addWidget(findButton);
rightLayout->addWidget(closeButton);
rightLayout->addStretch();
QHBoxLayout *mainLayout=new QHBoxLayout;
mainLayout->addLayout(LeftLayout);
mainLayout->addLayout(rightLayout);
setLayout(mainLayout);

}@

[SGaist]

Then, did you try to call qmake "Run qmake" from the "Build" menu of Qt Creator ?

[Project try]

Yes :( same problem

[SGaist]

Also with a "Rebuild All" ?

@#include <QtGui> << bad habit only include what you use@